The Backbone of Your Business
January 25, 1999
Links for
Additional Information
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Gigabit and ATM
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Data Communications, May 1 1998
Lab Test: ATM Switches/ATM: Brains and Brawn
Data Communications, May 1 1998
"ATM Net Management: Missing Pieces"
Network Computing, September 1, 1998
"Gigabit Ethernet Switches Set To Take
On the Enterprise,"
InternetWeek, October 19, 1998
"Gigabit Ethernet: Easy Does It,"
InternetWeek, November 16, 1998
"Gigabit Ethernet Races Along,"
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Quality of Service
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Network Computing, August 1, 1998
"Bringing Prioritization Services to Ethernet,"
Network Computing, August 15, 1998
"Implementing Prioritization on IP Networks,"
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Bandwidth Issues
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Internet Week, July 13, 1998
"Bandwidth Boom: Making the Connection,"
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VLAN technologies
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Network Computing, October 15, 1998
"Virtual Protection: CNU Tags Workgroups by VLAN,"
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Multicast and Multimedia
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Network Computing, June 1, 1998
"Casting Off Old Myths With IP Multicast,"
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Future Standards
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InformationWeek, October 19, 1998
"Strengthen Your Backbone,"
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That two competing technologies are pushing themselves on this emerging market complicates the future. Which technology will make the cut? The MT-RJ camp of more than 30 vendors includes big guns such as Cabletron Systems, Cisco Systems, Extreme Networks, Foundry Networks and Nortel Networks. Volition is backed by Allied Telesyn, Cisco, Olicom and others. Most vendors will likely support both, just as they support SC and ST connectors today. In the gigabit space, HP is shipping a gigabit MT-RJ connector, while 3M anticipated having samples in the fourth quarter of 1998. Vendors that use HP optics in their devices may support MT-RJ before VF-45, but the TIA (Telecommunications Industry Association) and consumers ultimately will decide if either connector will dominate the market.
No. 2: ATM, Gigabit or Hybrid?
If ATM isn't already part of your network, your best bet is to keep it that way. But if you've already made a significant investment in ATM, then a mesh of OC-12 ATM switches with Gigabit Ethernet uplinks to edge switches may be just what you need. Why gigabit uplinks? Keeping ATM at the core of your network reduces the number of management points and possible points of failure. Gigabit Ethernet is easier to manage, and provides more bandwidth per fiber than OC-12 ATM.
Few infrastructure debates have been more heated than Gigabit versus ATM, and vendors have done little to end the confusion: Cabletron, Cisco, FORE Systems, Nortel and 3Com all offer solutions in both areas. But despite the praise heaped on ATM for its QoS (Quality of Service), scalability and fault tolerance, ATM has fought an uphill battle since its inception. Interoperability and standards compliance have repeatedly driven nails into its proverbial coffin. Simply put, ATM is a single-vendor solution.
ATM's strengths on the LAN lie in PNNI (Private Network-to-Network Interface), a powerful Layer 2 routing protocol, and a scalable architecture that lets you add an unlimited number of links from one point to the next to increase bandwidth as needed. PNNI lets you mesh your network to provide multiple, load-balanced paths. In a well-designed ATM network running PNNI, you could remove one or more switches without disrupting network operations. Gigabit Ethernet touts Spanning Tree and proprietary methods of resiliency. Some systems offer recovery times on a par with PNNI, but a Layer 3 routing protocol generally provides the multipath intelligence for these systems.
 Gigabit Ethernet, on the other hand, scores points in the backbone battle with its familiarity and simplicity. It is nearly impossible to misconfigure an Ethernet connection. On the price-per-megabit front, Gigabit Ethernet ports are approaching the $1,000-per-port level, while ATM holds steady at about $500 per 155-Mbps port. In addition, this frame-based technology generally offers sufficient support for LAN-based QoS. Like ATM, Gigabit Ethernet features redundancy at Layer 2, but, unlike ATM, it cannot build a meshed network.
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